Sawmill log holder assembly

ABSTRACT

Apparatus for use in sawing a log including a log holder assembly having opposed upper and lower log-gripping members which are movable between vertically remote, inoperative positions and operative log-penetrating support positions, and incorporating mechanism for positively locking one of the gripping members in vertical position so that the gripping members provide the sole support for maintaining the log at a predetermined elevation while multiple cuts are being taken.

United States Patent 11 1' Smith Mar. 19, 1974 [54] SAWMILL LOG HOLDER ASSEMBLY FOREIGN PATENTS OR APPLICATIONS [75] lnvemorl leeward Smith, Remus M 1.219.824 4/1'959 France 269/542 Assignee: Morbark Industries Inc, Winn, 1,199,787 4/1959 France 269/541 M h. 10 Primary Examiner'Donald R. Schran [22] Filed: Dec. 13, 1971 [2i] Appl. No.: 207,395 [57] ABSTRACT 1 Apparatus for use in sawing a log including a log 52 U.S. c1 83/4041, 83/409, 83/435, holder assembly having opposed upper/and lower g- 5 54 5 4 gripping members which are movable between verti- 51 1111. c1. B27b 7/04, B27b 29/08 Cally te inoperative positions and Operative [58] Field of Search 269/53, 54, 54.1, 54.2, Penetrating pp Positions, and incorporating 269/54.3,54.4; 83/4041, 403.1, 409, 469, 435 mechanism for positively locking one o the pp g members in vertical position so that the gripping mem- 5 References Cited bers provide the sole support for maintaining the log UNITEDSTATES PATENTS at a predetermined elevation while multiple cuts are 1 being taken. 497.768 5/1893 Cole....; 83/404.l 3 v 1.944.287 H1934 Langill. 7 Claims, 12 Drawing Figures 1,962,329 6/1934 Sly 83/4041 1 PATENTEDMAR 19 I974 3797349 sum 1 [1F 3 INVENTOR LEWARD V. Sm T I Learmcm 6? McCullnch ATTORNEYS PATENIED m I 9 I974 SHEET 2 BF 3 INVENTOR n In Z M N. 6 0 0 m ATTORNEYS r I 1 SAWMILL LOG HOLDER ASSEMBLY FIELD OF THE INVENTION BACKGROUND OF THE INVENTION In the lumbering industry, logs of good quality are generally cut completely into boards, whereas logs of inferior quality are frequently squared for use as railroad ties, and the like. In present day sawmill operations, a log is conventionally squared by supporting it on a carriage and rolling it 90 about its longitudinal axis between successive longitudinal .cuts to successively remove the four slabs which subsequently are reduced to chip form in order to receive some economic return from them. A substantial amount of time is required to roll the log over and the time required for rolling approaches the time required for sawing, so that almost as much time is used for positioning the log as for sawing it. Accordingly, it is an object of the present invention to provide apparatus for use in squaring a log which will substantially reduce positioning time and increase production.

clamp a log supported on the bunks therebetween,

mechanismfor vertically locking either the upper or lower log-gripping dogs in operative log-gripping position, and a drive for relatively transversely moving the bunks and'the log-gripping dogs to withdraw the bunks from the log clamped by the gripping dogs so that the log to be cut is supported solely by the dogs and at the same level as previously.

The present invention may more readily be described by reference to the accompanying drawings in which:

FIG. 1 is an' end elevational view of a log-supporting carriage, having a log supported thereon, parts of one It is another object of the present invention to provide log sawing apparatus which can square a log without rolling it about its longitudinal axis.

It is yet another object of the present invention to provide versatile log sawing apparatus which can selectively cut the log into boards, square the log, or produce some combination thereof.

Prior art systems have been suggested for gripping a log between a pair of vertically spaced log-gripping dogs which are mounted for movement by a single power cylinder such that one of the dogs must initially engage the log to be cut before the other dog moves into gripping relation. This, of course, further decreases log-cutting efficiency. The prior art provides no apparatus for locking one of the dogsin position so that the log being cut can be solely supported by the dogs at a particular predetermined eleva'tion. Accordingly, it is. a still further object of thepresent invention to provide a log holder assembly including a pair of vertically movable log-gripping jaws, and apparatus for locking one of the jaws in position so that the log can be supported solely by the dogs.

It is still another object of the'present invention to provide opposed log-gripping jaws which are simultaneously, individually movable between vertically remote and log gripping positions to expedite the log processing operation.

Other objects and advantages of the present invention will become apparent as the description thereof proceeds. i I

SUMMARY OF THE INVENTION An apparatus and a method for sawing a log comprising: a longitudinally extending frame, longitudinally spaced, transversely extending support bunks on the frame for supporting a log to be cut, pairs of upper and lower log-gripping dogs vertically movable on the bunks between vertically remote-inoperative positions and positions engaging the log, power cylinders for moving the pairs of upper and lower log-gripping dogs between the remote and log -gripping positions to of a plurality of log-supporting bunks and part of one of a plurality of log-engaging knees, which are supported on the carriage, being broken away to more clearly illustrate one of the chains which are provided for transversely moving the knees on the log supporting bunks;

FIG. 2 is a side elevational view of the apparatus illustrated in FIG. 1;

I FIG. 3 is a sectional plan view of the apparatus illustrated in FIGS. 1 and 2, taken along the line 3-.-3 of no.2;v FIGS. 4 7 illustrate the sequential positions of a log which is squared according to a different method when held by the prior art log-holding apparatus;

FIGS. 8 and 9 illustrate sequential positions of the apparatus which is used to square a log supported by a log holder assembly constructed according to the present invention; l

FIG. 10 is a partly schematic,-secti onal side view taken along the line 10-10 of FIG. 2, including a schematic representation. of the fluid control circuit constructed according to the present invention;

FIG. 11 is an enlarged perspective view illustrating the saw blades simultaneously cutting three sides of a log being squared; and

FIG. 12 shows cuts which may be taken to produce both boards and a tie or beam.

DESCRIPTION OF THE PREFERRED EMBODIMENT I Referring now more particularly to the drawings and in the first instance to FIGS. 1 and 3, apparatus constructed according to the invention includes a log holding and moving assembly, generally designated 10, for holding and moving a log L (FIG. 1) toward a sawing station, generally designated 12, to be sawed by a vertical, rotatable, peripherally toothed'circular saw, generally designated .14, and a pair of horizontal, vertically spaced, peripherally toothed rotatable saws l6 and 18 (FIGS. 9 and 11). i

The log holding and moving assembly 10 includes a longitudinally movable carriage, generally designated 20, including a pair of side frame members 21 spanned by a pair of end frame members 23. A plurality of axles 22 fixed to the side frame members 21 support a plurality of rollers 24 which ride along a pair of laterally spaced, floor supported longitudinal rails 26. A plurality of longitudinally spaced, transversely disposed, logsupporting, hollow bunks 28 are fixed on the carriage 20 and span the side frame members 21. The bunks 28 each include a pair of spaced apart horizontal upper ways 28a and 28b,having a lateral chain accomodating groove 28c therebetween for a purpose to be presently described. a

Supported for transverse sliding movement on each of the bunks 28 is a log-supporting knee, generally designated 30. Each of the knees 30 includes a vertical knee plate frame 31 having a pair of oppositely disposed C-shaped guides 32, at the lower end thereof, for receiving the ways 28a and 28b. For transversely, simultaneously moving the knees 30 toward and away from a log L supported on the bunks 28, apparatus, generally designated M is provided, and includes a longitudinal, rotatable shaft 34 (FIGS. 1 and 3) joumaled in bearings 35, provided on one side of the carriage 20. A plurality of longitudinally spaced apart sprocket Wheels 36 are fixed to shaft 34. The knee moving apparatus M includes an idler sprocket 40 disposed interiorly of each hollow bunk 28 and fixed to a shaft 42 rotatably mounted on the bunk 28. A roller link chain 38, fixed at opposite ends 38a and 38b to the knee plate frame 31, is trained around each sprocket wheel 36, the idler sprocket wheel 40, and a pair of idler sprocket wheels 43 which are fixed to a pair of shafts 44 journaled in each of the knee plate frames 31. A source of power, such as an electrical motor 46, is supported on the carriage 20 and drive the shaft 34 and the sprocket wheels 40 which react with the chains 38 to force the chains 38 to be wrapped around the sprocket wheels 36 and 4050 as to transversely force the knees 30 to slide toward and away from a log L supported on the bunks 28.

Apparatus is provided on the log-engaging knees 30 for gripping a log L supported on the bunks 28 and includes opposed upper and lower dog assemblies, generally designated 50. The dog assemblies include opposed, conically shaped, log penetrating dogs or claws 52 fixed to support plates 54 which are C-shaped in plan and are slidably received on T-bars 55 fixed to the ends of the knee plates 31 adjacent the log L. The lower log-gripping support plates 54 are vertically moved by means of double-acting, fluid-operated cylinders 56 pivoted on horizontal supports 58 (FIG. 2), provided on the knee plates 31, and having piston rods 60 fixed to the horizontal connector members 54a on the lower plates 54.

The upper dog assemblies 50 are vertically movable by means of double-acting, fluid operated cylinders 64 fixed on knee supported plates 62 and including piston rods 65 connected with horizontal offset sections 66 which are rigidly connected with vertical plates 68 fixed to the upper log-gripping head supporting plates 54.

THE CONTROL SYSTEM The support plates 54, slidably mounting the dogs 50 on the T-bars 55, are moved'from the log-penetrating positions, illustrated in solid lines in FIG. 1, to the vertically remote, inoperative positions, illustrated in chain lines in FIG. 1, by the fluid operated cylinders 56 and 64. Referring now more particularly to FIG. 10, fluid for advancing and retracting the dog positioning cylinders 56 and 64 is provided by a motor driven, fluid pump 70 connected to a reservoir or tank 71 by a line 72 and providing fluid along a line 73 to a solenoid actuated, two-position, spring returned, four-way dog positioning valve 74. A return line 73 is also connected between the valve 74 and the tank 71. The output of the valve 74 is provided along a pair of lines 75 and 76. The line 75 is connected to the retract side of the dog positioning cylinders 56 and 64 by a pair of lines 77 and 77a. The advance sides of the dog positioning cylinder 56 and 64 are connected with the other lines 76 by a pair of lines 78 and 79.

A solenoid operated, two-position, spring returned, two-way locking valve 80 is connected in line 78. The solenoids 74a and 80a of the valves 74 and 80 are parallelly connected in lines 83 and 84 and are connected with a source of energizing voltage 82a by means of a conductor 82. A start switch 85 is connected'in the line 82. Connected in the line 84 is a time-delay circuit 86 which includes a normally open switch 86b,in the line 84. Circuit 86 has an operating coil 86a connected to the junction of conductors 82 and 84 and ground potential. Approximately 3 seconds after the time-delay coil 86a is energized, the switch 86b willclose to connect the locking valve solenoid 80a with the electrical power source 82 so that the spool of the locking valve 80 moves from the flow through position to the fluidblocking position. When the dog positioning and locking valves 74 and 80 are in their flow through positions, illustrated in FIG. 10, the upper and lower log gripping dogs 50 will be simultaneously moved to and held in their remote, inoperative positions illustrated in chain lines in FIG. 1. When the start switch 85 is closed to energize the solenoid 74a,the dog positioning valve 74 will be moved to the cross-over position so that the fluid is directed to the advance sides of the dog positioning cylinders 56 and 64 and the upper and lower log-gripping dogs 50 are moved to their operative, logpenetrating positions, illustrated in solid lines in FIG. 1. Approximately 3 seconds after the valve 74 is moved to the cross-over position, the locking valve 80 is moved to the fluid-blocking position such that the piston rod 60 is prevented from lowering or settling under the weight of the log L since there is no escape path for the fluid on the lower side of the cylinder 56.

The lower dog assemblies 50 will thus be locked in position and will vertically support a log L .when the knee-driving motor 46 has been operated to move a log Lfrom a bunk supported position, illustrated in FIGS. land 8, to a position removed from the bunks 23 as illustrated in F IG. 9. Moreover, the locking of cylinders 56 will provide a fixed reference point such that when the vertically spaced, horizontal saws l6 and 18 are moved vertically toward and away from each other to cut the edges of differing width boards, the upper and lower sets of log-gripping dogs 50 will be moved substantially the same distance relative to the reference point. If one of the upper and lower sets of dogs were not stationary so that the log might float to different levels, the operator would have tocontinually check the relative vertical positions of the log L and the saws l6 and 18 to insure that they were correctly positioned in operative cutting relation.

THE PRIOR ART Apparatus constructed according to the prior art is shown generally in FIGS. 4 7 and includes a logsupporting bunk 28' mounting vertically movable dogs 50', actuated by a single power cylinder, and slidably mounted on a support member 55. In order to cut a log L, the log L was moved toward the saw blade 14' so that a cut is first made along one side of the log as illustrated at 90 in FIG. 4. The log L is then turned 90 to the position illustrated in FIG. 5 and a second cut made as illustrated at 80A. The log is then turned 90, to the position illustrated in FIG. 6, and a third cut was made may be utilized as a railroad tie or the like.

THE OPERATION A log L is placed on the ends of the log-supporting bunks 28 and the knee advancing motor 46 is driven to advance the knees 30 to a position engaging the log L. At this time the log-engaging dog assemblies 50 are in their retracted positions, illustrated in chain lines in FIG. 1. The dog positioning valve 74 is then actuated to their flow-through positions'to direct fluid to the advance sides of the upper and lower dog advancing cylinders 56 and 64 along fluid supplying lines 77 and 77a respectively. After the log-penetrating dogs 50 are moved to their log-penetrating positions, illustrated in solid lines in FIG. 1, the cylinder locking valve 80 is operated, after a short time delay to permit the dogs and log to take final positions, to move its spool to the blocking position to absolutely prevent fluid from returning along the line 79 to the tank 71. The carriage is'then longitudinally advanced toward the rotatable, vertical saw blade 14 so that the first cut is made, as illustrated at 98 in FIG. 8, to remove a slab 95. The carriage is then retracted longitudinally and the knee advancing motor 46 is again energized to advance the log L and move it off the bunks 28 to the position illustrated in FIG. 9. The carriage 20 is again moved longitudinally forwardly tothe log sawing station where the horizontal saws 16 and 18 provide horizontal cuts 98a and 98b, while the vertical saw blade 14 simultaneously provides a vertical cut 980 on the opposite side of the log to remove upper and lower slabs 93 and 94, and side slab 100, to provide a squared log portion orcant L'. The log is thus squared without having to 'rollit about its longitudinal axis as is the case in the prior art method, illustrated in FIGS. 4 7.

As illustrated in FIG. 12, when some usable board lumber can be obtained, and the cant log L" can. be cut such that its height h is greater than its width w, the former slab? portion 95 is cut into boards by repeatedly moving the carriage20 toward and away from the sawing station while incrementally moving theknees 30a relatively less'transverse distance, equal to the width of the board to be out, between strokes of the carriage. Between strokes, the blades 16 and 18 are incrementally moved apart, to positions-designated 105a, 105b, and 106a, l'llfib respectively, to adjust to the increasing diameter of the log being cut so that a wider board is sawed on each successive pass and the maximum board-feet are cut from a given log. After the boards 102 and 103 have been cut, the knees 30 are advanced a substantial distance so that the vertical saw 14 will provide a vertical cut 108 and the saws l6 and 18 are vertically moved apart to provide cuts 109 and 110 to provide a squared log section L. I

The upper and lower saw blades 16 and 18 are then moved vertically closer together and the knees 30 are advanced incremental distances equal to the thickness of a board B to cut the final two boards 105 and 106. Because the lower dog assemblies 50 are locked in position, when the upper and lower blades 16 and 18 are moved vertically the same distance, but ,in opposite directions, the blades will also be moved vertically the same distance relative to the log L. If one of the upper and lower sets of dog assemblies were not locked and 6 the log L could float vertically, the positions 'of the saws l6 and i8 would have to be adjusted to account for the movement of the log L. This, of course, would be timeconsurning and would impair sawing efficiency.

Log holding apparatus constructed according to the present invention provides increased versatility by enabling the machine operator to either cut the log L into boards or to square the log, and in each instance withv out rotating the log.

it is to be understood that the drawings and destripments to achieve like results without departing from the spirit of the invention or the scope of the appended claims.

I claim:

ll. Apparatus for use in performing sawing operations on a log, at a sawing station comprising:

sawing means at said sawing station;

a carriage movable in alongitudinal path of travel toward and away from saidsawing means at said sawing station;

upper and lower log penetrating; clamps mounted on said carriage for-individual vertical movement between removed inoperative positions and operative, log penetrating positions; 1

first and second independently operative motor means supported by said carriage for individually moving said upper and lower log-engaging clamps between said removed. inoperative positions and said operative log-penetrating positions to clamp said log therebetween; and

imeansfor selectively locking one of said upper and lower clamps in said operative log-penetrating poi sition to prevent it from lowering so that the clamps do not lower when a log is supported entirely thereon.

2. The apparatus of claim 1 wherein said upper and lower clamping means comprises a pair of generally conically shaped log penetrating heads.

3. The apparatus of claim 1 wherein said motor means comprises first and second fluid pressure operated motors for respectively moving said upper and lower log'gripping means in forward and reverse paths of travel to advance and retract the upper and lower log-gripping means to and from said log; said locking means comprising means for selectively preventing fluid flow to and from said second motor means to positively preclude its vertical movement.

4. The apparatus of claim 1 wherein the motor means for said lower clamp comprises fluid operated means movable in a forward and reverse path of travel to respectively advance and retract the lower clamp to and from said log; said locking means comprising means for selectively blocking the flow of fluid from said fluid operated means to prevent the lower clampfrom lowering under the weight of the log supported thereby.

5. A method of cutting a log comprising the steps of: supporting a log in longitudinal disposition from beneath; gripping upper and lower sides of the log at one lateral side thereof with log supporting grippers; removing the support below said log so that the major portion of said log laterally overhangs said gripper; and then 7 squaring the log by relatively longitudinally moving the log and saw blade means into cutting engagement without rolling the log about its longitudinal axis. 6. Apparatus for use in performing sawing operations on a log at a sawing station comprising:

a workpiece therebetween and 'provide the only vertical support therefor; and

first and second individually operative motor means on said frame for individually, simultaneously moving said upper and lower loggripping means between said removed and workpiece penetrating positions.

7. The apparatus of claim 1 including means for moving one of said carriage and said sawing means toward and away fromeach other; said sawing means including a plurality of circumferentially disposed saw blade means for squaring said log without rotating the log about its longitudinal axis as said sawing means and said carriage are moved together. 

1. Apparatus for use in performing sawing operations on a log, at a sawing station comprising: sawing means at said sawing station; a carriage movable in a longitudinal path of travel toward and away from said sawing means at said sawing station; upper and lower log penetrating clamps mounted on said carriage for individual vertical movement between removed inoperative positions and operative, log penetrating positions; first and second independently operative motor means supported by said carriage for individually moving said upper and lower log-engaging clamps between said removed inoperative positions and said operative log-penetrating positions to clamp said log therebetween; and means for selectively locking one of said upper and lower clamps in said operative log-penetrating position to prevent it from lowering so that the clamps do not lower when a log is supported entirely thereon.
 2. The apparatus of claim 1 wherein said upper and lower clamping means comprises a pair of generally conically shaped log penEtrating heads.
 3. The apparatus of claim 1 wherein said motor means comprises first and second fluid pressure operated motors for respectively moving said upper and lower log-gripping means in forward and reverse paths of travel to advance and retract the upper and lower log-gripping means to and from said log; said locking means comprising means for selectively preventing fluid flow to and from said second motor means to positively preclude its vertical movement.
 4. The apparatus of claim 1 wherein the motor means for said lower clamp comprises fluid operated means movable in a forward and reverse path of travel to respectively advance and retract the lower clamp to and from said log; said locking means comprising means for selectively blocking the flow of fluid from said fluid operated means to prevent the lower clamp from lowering under the weight of the log supported thereby.
 5. A method of cutting a log comprising the steps of: supporting a log in longitudinal disposition from beneath; gripping upper and lower sides of the log at one lateral side thereof with log supporting grippers; removing the support below said log so that the major portion of said log laterally overhangs said gripper; and then squaring the log by relatively longitudinally moving the log and saw blade means into cutting engagement without rolling the log about its longitudinal axis.
 6. Apparatus for use in performing sawing operations on a log at a sawing station comprising: support means for supporting a log to be cut; sawing means at said sawing station; and means for moving one of said log support means and said sawing means toward and away from each other; said support means comprising: a frame; upper and lower log-gripping means mounted on said frame for individual vertical movement between vertically removed inoperative positions and operative, log-penetrating positions to clamp a workpiece therebetween and provide the only vertical support therefor; and first and second individually operative motor means on said frame for individually, simultaneously moving said upper and lower log-gripping means between said removed and workpiece penetrating positions.
 7. The apparatus of claim 1 including means for moving one of said carriage and said sawing means toward and away from each other; said sawing means including a plurality of circumferentially disposed saw blade means for squaring said log without rotating the log about its longitudinal axis as said sawing means and said carriage are moved together. 